This invention relates to a voltage switching device which includes a gas discharge panel of a type similar to that known as a gas discharge or plasma display panel. The gas discharge panel included in a voltage switching device in accordance with this invention is different from a conventional gas discharge display panel in that the former does not necessarily show a display as is the case with a control portion of a gas discharge display panel of the type disclosed in copending U.S. patent application Ser. No. 555,139, now U.S. Pat. No. 3,976,971. A voltage switching device according to the present invention is useful in applying a relatively high voltage to a selected one or ones of a plurality of electrodes, such as in the selection of electrodes of a gas discharge display panel or in the scanning of electrodes of an electrostatic printer.
A gas discharge display panel comprises at least one first electrode and a plurality of second electrodes disposed opposite to the first electrode. A plurality of spaces defined by the first and second electrodes are filled with an ionizable gas to serve as gas discharge spaces or cells. In order to make such a gas discharge display panel provide a desired display, a voltage switching device is necessary to supply a voltage higher than the firing voltage of the cells across those one or ones of the cells which are selected in accordance with the desired display. Under these circumstances, each of the cells corresponds to a picture element of the displays. A conventional voltage switching device for use in selecting the cells of the panel comprises either a plurality of switching transistors or a diode matrix adapted for connection to the respective electrodes of the panel. With an increase in the number of electrodes of the panel, a corresponding increase has been necessary in the number of elements, such as the transistors or diodes, of the voltage switching device. As a result, there have been problems and drawbacks with the conventional voltage switching device with respect to the reliability and cost of the device and the difficulty in connecting the device to the electrodes of the display panel.
A color gas discharge display panel for producing colored displays comprises a set of a predetermined number of gas discharge cells for each picture element of the displays. The cells of each set comprise the predetermined number of layers of luminescent materials of different colors, such as red, green, and blue. A device for making the panel display a desired colored display comprises means for selecting a desired one or ones of the cell sets and means for selecting a combination of cells in each selected cell set. The selection of a desired cell combination has to be carried out for each selected cell set so that each picture element may be displayed in a desired color. In other words, the selection of a picture element has to be accompanied by the selection of the color of the selected picture element. This has complicated the voltage switching device.
An electrostatic printer of an electronically scanned type is preferred to a mechanically scanned multi-stylus electrostatic printer and to an electrostatic printer comprising an electrostatic recording cathode-ray tube. As pointed out in U.S. Pat. No. 3,750,190 an electrostatic printer of the mechanical scanning type is disadvantageous with respect to its short service life and to troubles in its maintenance. An electrostatic recording cathode-ray tube is objectionable as the necessity of a very high voltage for putting the cathode-ray tube into operation and difficulties in adjusting the operation of the tube. A device for switching a voltage that is sufficiently high for electrostatic recording is very desirable for electronically scanning electrodes, such as the styli, of the printer while successively supplying the electrodes with signals that are to be recorded.